1. Field of the Invention
The present invention relates generally to a surgical stapler for applying surgical staples to tissue. More particularly, the present invention relates to a surgical stapler which is attached to an endoscope. The present invention has particular application to transanal or transoral surgical procedures, although it is not limited thereto.
2. State of the Art
It has been long known in the surgical arts that surgical staplers provide an expeditious and efficient way of joining or repairing tissue. In fact, in certain types of surgical procedures, the use of surgical staples has become the preferred method of joining tissue as opposed to suturing. A common use of surgical staplers relates to the repair of the colon after a portion of the colon has been removed. For example, when a tumor is found in the colon, it is not uncommon to remove a large portion of the colon. The remaining sections of the colon are then joined together in a surgical procedure called anastomosis, where the tubular sections are joined together to form a continuous tubular pathway.
In the anastomosis procedure, the abdominal cavity of the patient is typically opened to expose the diseased portion of the colon. The diseased portions of the colon are then surgically removed, and the remaining portions of the colon are joined together. Prior to the use of staplers, the anastomosis procedure was laborious and lengthy as the surgeon had to cut and precisely align the ends of the intestine and maintain the alignment while joining the ends with sutures. The development of circular staplers greatly simplified the anastomosis procedure by permitting the surgeon to simultaneously provide one or more rows of staples which join sections of the colon while cutting away excess tissue which would otherwise occlude the tubular passageway. However, even with the use of the circular stapler, it is still necessary to create an access port in an otherwise healthy portion of the colon for entry and removal of the stapler. After the stapler is used for anastomosis, and then removed from the colon through the access port, it is necessary to repair the colon at the access port via suturing or linear stapling.
Many different circular staplers are known in the art, and several are commercially available. For example, circular staplers are sold under the PROXIMATE brand by Ethicon Inc., Somerville, New Jersey such as are described in U.S. Pat. No. 5,205,459 to Brinkerhoff et al., U.S. Pat. No. 5,261,920 to Main et al., U.S. Pat. No. 5,271,544 to Fox et al., U.S. Pat. No. 5,285,945 to Brinkerhoff et al., U.S. Pat. No. 5,333,773 to Main et al, and U.S. Pat. No. 5,445,644 to Pietrafitta et al., all of which are hereby incorporated by reference herein in their entireties. Other circular staplers are sold under the AUTO SUTURE brand by United States Surgical Corporation, Norwalk, Conn. and are described in U.S. Pat. No. 4,576,167 to Noiles, U.S. Pat. No. 5,005,749 to Aranhi, U.S. Pat. No. 5,193,731 to Aranyi, U.S. Pat. No. 5,360,154 to Green, U.S. Pat. No. 5,443,198 to Viola et al., U.S. Pat. No. 5,437,684 to Calabrese et al., U.S. Pat. No. 5,447,514 to Gerry et al., U.S. Pat. No. 5,454,825 to Van Leeuwen et al., and U.S. Pat. No. 5,474,223 to Viola et al., all of which are also hereby incorporated by reference herein in their entireties. Generally common to all circular staplers are several elements, including a staple head assembly, a shaft assembly, and a handle assembly. The staple head assemblies all include a staple holder which holds a plurality of staples arranged around a circular periphery, a circular anvil which acts to form the ends of staples driven through the tissue, a circular knife or scalpel, and a driver which drives the staples from the staple holder and actuates the knife. The shaft assembly typically includes a substantially rigid longitudinally curved shaft which holds a tension member for transmitting tension from an actuator handle to the anvil to resist forces on the anvil, a compression member for transmitting a compressive force from the actuator handle assembly for advancing the staple driver to drive the staples into the tissue and to drive the knife through the tissue adjacent the staples. The handle assembly typically includes a handle, and one or more levers and/or knobs. The levers and knobs are used for moving the anvil relative to the staple holder, and for firing the staples and the knife.
While great improvements in circular staplers have been made over the years, it will be appreciated by those skilled in the art that the anastomosis procedure is still an extremely invasive procedure which leaves both external and internal scars. Indeed, not only must the abdominal cavity be opened, but a large segment of the colon is typically removed to avoid the possibility of recurrence, as recurrence would lead to another traumatic surgery. Moreover, as described above, the colon must be punctured at a healthy location to provide a port for the circular stapler, and this puncture must then be sutured or stapled (as must the abdominal cavity).
Clearly, it is desirable to avoid excessive trauma to healthy portions of the colon during the anastomosis procedure. Toward that end, various flexible surgical staplers have been proposed which theoretically can be introduced transanally such that the colon need not be punctured at a healthy location to provide an access port for the stapler. These flexible shaft staplers are disclosed inter alia in U.S. Pat. No. 4,671,445 to Barker et al., U.S. Pat. No. 4,473,077 to Noiles et al., U.S. Pat. No. 4,488,523 to Shichman, U.S. Pat. No. 4,754,909 to Barker et al., U.S. Pat. No. 5,258,008 to Wilk, U.S. Pat. No. 5,271,543 to Grant et al., and U.S. Pat. No. 5,433,721 to Hooven et al., and PCT application WO 93/15668 to Blanco et al., all of which are incorporated by reference herein in their entireties. While these flexible shaft staplers provide one advantage, they do not obviate the need for abdominal surgery, as when the stapler is in place, there is no manner of viewing the surgical site other than via laparoscopic or open abdominal surgery. In addition, the flexible shaft staplers suffer from other shortcomings. In particular, some of the flexible shaft staplers do not have long shafts which would permit them to reach well up into the colon. Others of the flexible shaft staplers have shaft assemblies which are cumbersome and/or impractical and expensive to build. Others of the flexible shaft staplers have stiffening problems due to the force required for the simultaneous firing of multiple staples which are circumferentially disposed. Regardless of the particular nature of the shortcomings, they have apparently been such that the flexible shaft staplers have not been commercially successful.
In a similar vein to the flexible surgical staplers is U.S. Pat. No. 5,197,649 to Bessler et al. which is hereby incorporated by reference herein in its entirety, and which provides a steerable endoscopic stapler which is introduced via the rectum, but which requires that the diseased portion of the colon be already removed using invasive surgical tools. The steerable endoscopic stapler of Bessler et al. proposes a custom instrument which includes the basic steering and ocular capabilities of a standard endoscope, a circular staple head assembly at the distal end of the endoscope, and a cable and pulley system for bringing the anvil and stapler of the staple head together and firing the staples and knife. While the concept of combining the visual apparatus of the endoscope with the stapler in a single device has certain advantages, it will be appreciated by those skilled in the art that an entire re-engineering of the commonly used endoscopes is undesirable. Indeed, staplers are typically disposable instruments because of difficulties in cleaning and controlling critical dimensions, while endoscopes are very expensive reusable instruments. A combination instrument as proposed by Bessler et al. would therefore be economically unfeasible as cleaning and sterilization of the device would be impossible. In addition, the mechanics of the device proposed by Bessler et al. has numerous drawbacks which make it impractical. For example, while the single cable and pulley system will ostensibly work to bring the anvil and stapler together and then fire the staples and knife, there is no mechanism provided for opening the anvil relative to the stapler after stapling. Further, while no sizes are mentioned, it would appear (by comparing the relative sizes of the flexible endoscope shaft portion and the head portions) that the head portion of the stapler is undesirably large (e.g., three times as large as the flexible shaft), and would present major steering problems. Finally, it is impossible to perform a full 360.degree. anastomosis endoluminally without the aid of other surgical techniques. One side of the exterior surface of the bowel is attached to the mesenteric vascular arcade which must be detached from the bowel before performing anastomosis. There is no known way to perform the detachment other than via open or laparoscopic surgery.
In order to avoid the trauma of abdominal surgery completely, it has been suggested that a flexible endoscopic stapler be provided over an endoscope, such that both the stapler and endoscope are introduced via the rectum and no incisions are required. Such a flexible endoscopic stapler would include a head assembly, a flexible tubular member, and a proximal control assembly. The flexible tubular member would include numerous lumena, including a large lumen for receiving a standard type endoscope which moves relative to the stapler, and smaller lumena for receiving forceps instruments, cables, steering elements for the head assembly, etc. The head assembly would include a clamshell (elongated truncated ellipsoid) shaped stapler head and a similarly shaped anvil which are hinged relative to each other. The staples would be located in a cartridge placed in the stapler head, and assume two rows forming a quarter circle curve and a straight line extending from the quarter circle curve. The anvil would be provided with a similar configuration. A knife would moves along a similarly shaped track inside of the staples. The stapler head would moved relative to the anvil (or vice versa) utilizing a cable and pulley arrangement in conjunction with a bevel gear. The proposed device would not be intended to perform an anastomosis, but rather would provide a full tissue resection and stapling repair of a smaller portion of the colon without requiring invasive abdominal surgery (i.e., an incision). It is believed that full tissue resections of the diseased portions of the colon should be a sufficient treatment where invasive abdominal surgery can be avoided, as the treatment is less traumatic and can be repeated if necessary.
While the proposed full tissue resection device would provide a conceptual improvement over the prior art, it would still suffer from several drawbacks. First, a clamshell shaped arrangement with a hinged stapler head and anvil is non-optimal for several reasons. First, with a hinged arrangement, tissue is forced outward from the stapler as the stapler is closing, thereby risking a failure to obtain the desired tissue. Second, with the hinged arrangement the overall diameter of the clamshell and the stapler device is increased dramatically when the stapler is opened, thereby risking tearing of non-diseased tissue. Third, alignment of the staples with the receivers in the anvil is extremely difficult because the stapler head and anvil will not always close to the same location (i.e., depending on the amount and density of the tissue trapped therebetween). In addition, with a clamshell shaped hinged stapler, the mechanics of the stapler head are at best difficult and unwieldy. In particular, the stapler arrangement with a curved section and a straight section leads to issues regarding the shape of the knife and the staple driver. Likewise, the cable and pulley arrangement with the bevel gear for opening and closing the stapler head is extremely complex and consumes large amounts of space within the device. Further, it will be appreciated that because of all of the mechanical issues, the head of such a stapler device would be extremely large and unlikely to be able to be steered significantly into the colon. Finally, it will be appreciated that because the complexities of such a device, including the steering abilities, etc., the cost of manufacturing a disposable device would be extremely large, thus reducing the likelihood of its commercial acceptance.